Tractor mounted scraper blade

Abstract

A material handling assembly has a frame for attachment to the three point hitch of a tractor. A laterally swingable boom extends rearwardly from the frame and has an upright shaft at its rear end rotatable about an upright axis for suspending a reversible scraper blade whose angularity may be varied as the shaft is rotated. The blade is releasably attached to and tiltable relative to the shaft. All four functions of raising and lowering the frame, swinging the boom, varying the angularity of the blade and tilting the blade are hydraulically controlled. A special four bar linkage coupled with the shaft provides for wide blade angularity adjustment. A fluid bypass arrangement interconnects the swing and angularity functions to accommodate for excessive loads which may be encountered when the attitude of the blade is to be varied in accordance with desired grading operations.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is: 
     
       1. In a material handling assembly; a swingable boom;   a first unit for swinging the boom in opposite directions;   an elongated scraper blade having means pivotally supporting the same on the boom for swinging movement therewith and with respect thereto;   a second unit;   a coupling between the second unit and the blade for swinging the latter in opposite directions relative to the boom during actuation of the second unit, to and from a position placing its longitudinal axis in perpendicular relationship to the normal course of travel of said assembly in all positions of swinging movement of the boom, and for placing said axis substantially parallel to said course when the boom is swung toward either end of its path in swinging movement,   said units each comprising a first and a second double acting fluid pressure piston and cylinder means, each provided with a reciprocable piston rod extending from one end thereof,   each cylinder having a pair of fluid receiving lines, one communicating with the rod end thereof and the other communicating with the piston end thereof, said lines being adapted for connection with a source of fluid under pressure;   manually operable valving coupled with said lines for controlling the flow of said fluid to and from each end of each cylinder respectively; and   relief valving coupled with said lines for bypassing fluid between the cylinders when the resistance to swinging movment of the boom or the blade in either direction exceeds a predetermined amount.   
     
     
       2. In a hydraulic system: a first and a second double acting, hydraulic cylinder,   each cylinder having a reciprocable piston rod extending from one end thereof with each rod being adapted for coupling with a corresponding load,   each cylinder having a rod line communicating with its rod end and a piston line communicating with its piston end for flow of hydraulic fluid to and from the cylinders;   relief valving coupled with said lines for bypassing fluid from each cylinder to the other when the loads on the rods exceed predetermined amounts,   said relief valving being coupled with said lines to bypass fluid from the rod end of each cylinder to the rod end of the other cylinder respectively and from the piston end of each cylinder to the piston end of the other cylinder respectively during operation of the relief valving,   said relief valving including a pair of relief valving components,   each component having a pair of relief valves,   one relief valve of the first of said components discharging to the rod line of said first cylinder,   the other relief valve of said first component discharging to the rod line of the second cylinder,   one relief valve of the second of said components discharging to the piston line of said first cylinder,   the other relief valve of said second component discharging to the piston line of said second cylinder; and   structure permitting either separate and independent or contemporaneous operation of said cylinders including: a first manual valve having a first connection with the rod line of the first cylinder and a second connection, separate from the first connection, to the piston line of the first cylinder, and   a second manual valve having a first connection with the rod line of the second cylinder and a second connection, separate from said last mentioned connection, to the piston line of the second cylinder,   each valve being adapted for connection with a source of hydraulic fluid under pressure and with a return to said source.     
     
     
       3. The invention of claim 2; a swingable boom;   means coupling the first cylinder with said boom for swinging the latter in opposite directions;   an elongated scraper blade swingable on the boom; and   means connecting the second cylinder with the blade for swinging the latter in opposite directions.